tinyformat: Add doc to Bitcoin Core specific strprintf
tinyformat: Add doc to Bitcoin Core specific strprintf

Github-Pull: #16205
Rebased-From: fa72a64b90dc07a80b1ca6127eb50d8244dedc3b

myriadcoin/myriadcoin,myriadteam/myriadcoin,myriadcoin/myriadcoin,vertcoin/vertcoin,untrustbank/litecoin,ahmedbodi/vertcoin,untrustbank/litecoin,bespike/litecoin,GroestlCoin/bitcoin,myriadcoin/myriadcoin,qtumproject/qtum,myriadteam/myriadcoin,GroestlCoin/GroestlCoin,ahmedbodi/vertcoin,vertcoin/vertcoin,qtumproject/qtum,qtumproject/qtum,myriadcoin/myriadcoin,qtumproject/qtum,bespike/litecoin,ahmedbodi/vertcoin,myriadteam/myriadcoin,vertcoin/vertcoin,bespike/litecoin,myriadcoin/myriadcoin,GroestlCoin/bitcoin,vertcoin/vertcoin,ahmedbodi/vertcoin,GroestlCoin/GroestlCoin,GroestlCoin/bitcoin,bespike/litecoin,qtumproject/qtum,GroestlCoin/GroestlCoin,GroestlCoin/GroestlCoin,vertcoin/vertcoin,myriadteam/myriadcoin,myriadteam/myriadcoin,myriadteam/myriadcoin,untrustbank/litecoin,ahmedbodi/vertcoin,GroestlCoin/bitcoin,untrustbank/litecoin,myriadcoin/myriadcoin,GroestlCoin/bitcoin,untrustbank/litecoin,bespike/litecoin,vertcoin/vertcoin,ahmedbodi/vertcoin,GroestlCoin/GroestlCoin,qtumproject/qtum,untrustbank/litecoin,qtumproject/qtum,GroestlCoin/bitcoin,GroestlCoin/GroestlCoin,bespike/litecoin